1. Field of the Invention
The present invention relates to an ink jet printer provided with a print head which ejects ink, and more specifically to an ink jet printer which confirms an electrical connection at the time of mounting a detachable print head on a carriage on a printer main body.
2. Description of the Related Art
An ink jet printer (hereinafter also referred to simply as a printing apparatus) is a printing apparatus which carries out the printing on a print medium by mounting a print head which ejects ink from an ejection port on a carriage, and causing the carriage to travel in parallel with a platen which supports the printing medium at the time of printing. There is a print head structured so that the carriage can be detachable thereto, and an electrode for electrical connection with the carriage is provided on the print head. The electrode of the print head is brought into contact with an electrode with an elastic action which is provided on the carriage, so that the electrical connection with the printing apparatus main body is established to transmit a signal and supply power from the printing apparatus to the print head.
In such a printing apparatus in which the print head can be replaced, mounting operation of the print head by a user is carried out at the time of initial installation and replacing the print head because of the end of life of the print head. At that time, it is highly likely that ejection cannot be done properly if inadequacy occurs in mounting of the print head to generate a poor connection in a part of connection elements. Therefore, in this case, it is preferable to give a user notice of inadequate mounting of the print head in the early stage after the mounting.
As a technology for addressing such a problem, Japanese Patent Laid-Open No. 2006-297826 discloses a method for confirming an electrical connection between a print head and a printing apparatus using a connection terminal located in the corner of the print head as a terminal for detecting the contact. Also, there is a method in which a pattern for confirming the ejection from an ejection port is printed in the state where ink is charged to the print head, and a poor connection of some of connection terminals is recognized on the basis of the printed result.
However, the method disclosed in Japanese Patent Laid-Open No. 2006-297826 merely confirms an alignment on a connection surface to determine the status of mounting the print head. It is thus impossible to sense the connection status of individual terminals in detail, such as inclusion of tiny flecks of waste. In actuality, the print head is hardly mounted to be significantly inclined in terms of mechanical structure, and most of poor connections may depend on individual terminals. Then, when the poor connections occur in the individual terminals, a user confirms a printed object to recognize that proper printing has not been done, or a user is notified the sensed result by an automatic ejection sensing function in the conventional case. Then, a user remounts the print head as an action for addressing it afterwards.
In such a press contact type of connection mechanism, although a number of measures other than that is taken to prevent the individual poor connections, the poor connections have not been completely eliminated. However, the press contact type of connection mechanism is widely used on the grounds of easiness of removability and low cost, while being press contact type makes it difficult to completely eliminate the poor contact due to inclusion of tiny flecks of waste.
Therefore, assuming that the remounting by a user is admitted as described above, the user may face the following two disadvantages. One is that replacement operation has to be performed after temporarily releasing ink supplied to the print head if the poor contact is revealed after the actual printing or automatic detection of the ejection. This of course results in waste of ink.
The other disadvantage is that the contact is confirmed merely after supplying ink to the print head, and the occurrence of the poor connection accordingly leads to significant extension of preparation time in total. In other words, the problem to be solved is in what way the poor contact of the connection terminal can be detected before starting the supply of ink to the print head.